Visualizing Information on a Sphere

We describe a method for the visualization of information units on spherical domains which is employed in the banking industry for risk analysis, stock prediction and other tasks. The system is based on a quantification of the similarity of related objects that governs the parameters of a mass-spring system. Unlike existing approaches we initialize all information units onto the inner surface of two concentric spheres and attach them with springs to the outer sphere. Since the spring stiffnesses correspond to the computed similarity measures, the system converges into an energy minimum which reveals multidimensional relations and adjacencies in terms of spatial neighborhoods. Depending on the application scenario our approach supports different topological arrangements of related objects. In order to cope with large data sets we propose a blobby clustering mechanism that enables encapsulation of similar objects by implicit shapes. In addition, we implemented various interaction techniques allowing semantic analysis of the underlying data sets. Our prototype system IVORY is written in JAVA, and its versatility is illustrated by an example from financial service providers

Interactive Visualization of Multidimensional Feature Spaces

Image similarity models characterize images as points in high-dimensional feature spaces. Each point is represented by a combination of distinct features, such as brightness, color histograms or texture characteristics of the image, etc. For the design and tuning of features, and thus the effectiveness of the image similarity model, it is important to understand the interrelations of individual features and the implications on the structure of the feature space. In this paper, we discuss an interactive visualization tool for the exploration of multidimensional feature spaces. Our tool uses a graph as an intermediate representation of the points in the feature space. A mass spring algorithm is used to layout the graph in a 2D space in which arrangements of similar images are attracted to each other and dissimilar images are repelled. The emphasis of the visualization tool is on interaction: users may influence the layout by interactively scaling dimensions of the feature space. In this way, the user can explore how a feature behaves in relation to other features

From visual data exploration to visual data mining: a survey.

We survey work on the different uses of graphical mapping and interaction techniques for visual data mining of large data sets represented as table data. Basic terminology related to data mining, data sets, and visualization is introduced. Previous work on information visualization is reviewed in light of different categorizations of techniques and systems. The role of interaction techniques is discussed, in addition to work addressing the question of selecting and evaluating visualization techniques. We review some representative work on the use of information visualization techniques in the context of mining data. This includes both visual data exploration and visually expressing the outcome of specific mining algorithms. We also review recent innovative approaches that attempt to integrate visualization into the DM/KDD process, using it to enhance user interaction and comprehension

Proximity Map Projection: Interactive Visualisation for Image-Guided Surgery

This thesis describes a new interface technique for neurosurgeons and interventional radiologists performing image-guided therapies such as the ablation of brain tumours. This new technique is called Proximity Map Projection (PMP). Based on an analysis of related work, including the documented recent progress in enabling technologies, a case is made that present-day interactive visualisations supporting image-guided treatment of tumours will need to be dramatically improved to take advantage of the increased image refresh rates available as soon as 2020. This probable requirement for improved visualisation technology in the very near future motivated the invention and investigation of the PMP technique described in this thesis. The PMP technique is an interactive 2-D visual projection of the proximity of two 3-D surfaces – in particular, the surface representing the boundary of a thermal treatment region, and the surface of a tumour that is the target of this treatment. By clicking on interesting points in the PMP, surgeons are able to quickly select the 2-D MRI slices corresponding to those interesting points. The PMP provides a quick way of selecting a desired image from a large stack of 2-D MRI data, thus freeing up surgeons to spend a greater proportion of their time applying their expertise to decision making, rather than to navigating through image data. In this thesis, the PMP technique is presented and then refined as user studies are undertaken. In a series of investigations exploring its effectiveness, it is shown that the PMP technique enables non-expert users to quickly and accurately navigate to, and observe, desired individual medical images within large stacks of such images. A further experiment finds no significant differences in the way that medically experienced and inexperienced users use PMP to complete tasks. That study also verifies that users pay visual attention to PMP, regardless of whether or not they have interacted with it via the mouse. Observation of the visual attention of users during simulated tasks is used to provide further explanation of why PMP is effective. PMP’s potential to be used by medical professionals is then assessed via a series of semi-structured interviews with surgeons and interventional radiologists. Such experts are found to be optimistic about the potential for PMP to be incorporated into their workflows. This last phase of the research then culminates with observations of a number of medical procedures on human patients that are similar to the kinds of procedures to which PMP might be applied. From these observations it appears that, while they do enable life-saving therapies, present software interfaces are not entirely satisfying for the surgeons who use them. Opportunities for significant future research collaborations were identified during these interviews and observations. This thesis concludes by describing a practical path towards achieving its ultimate goal: the use of PMP in real-time image-guided medical procedures on human patients. Key activities on this path include: integration of PMP into the training and simulation version of a collaborator’s therapy system; conducting a case study to allow further refinement of the PMP technique; and inclusion of PMP in a clinical trial with surgeons

Visualisierung komplexer Datenstrukturen in einer CAVE am Beispiel von Graphen

Diese Arbeit befasst sich mit der Konzeption eines Gestaltungskonzeptes für die Visualisierung komplexer zusammenhängender Datenmengen, wie sie durch Graphen repräsentiert werden können. Als Ausgabemedium wird dazu das immersive VR-System CAVE genutzt, welches es dem Betrachter ermöglicht, die Daten stereoskopisch und damit räumlich zu betrachten. Zur Entwicklung eines Gestaltkonzeptes für Graphen werden sowohl Besonderheiten der Raumwahrnehmung in VR-Systemen als auch Anforderungen und Aufgaben auf Graphen beleuchtet. Zusätzlich entstand ein Modell zur Klassifizierung von Graphenanwendungen sowie ein innovatives Konzept zur Darstellung von großen zweidimensionalen Graphen in einer CAVE. Als Resultat werden grundlegende Gestaltungskriterien angeboten, die es ermöglichen sollen, eine intuitive und effektive Visualisierung von Graphen zu realisieren.:1. Einleitung 1.1. Zielstellung 1.2. Gliederung 2. Grundlagen und Begrife 2.1. Informationsvisualisierung 2.2. Graphentheorie 2.3. Graphenlayout 2.4. Wahrnehmungundpsychologische Grundlagen 2.5. 3D Computergrafik 2.6. Stereo Grafik 2.7. Virtuelle Realität 2.8. Das Medium CAVE 3. Verwandte Arbeiten 3.1. ConeTrees 3.2. Information Cube 3.3. Hyperbolic Layout-H3 viewer 3.4. Skyrails 3.5. Perspective Wall 4. Synthese 4.1. Einführung 4.2. Einsatzgebiet für Graphen 4.3. Arbeiten mit Graphen 4.4. Mehrwert der dritten Dimension 4.5. Allgemeine Gestaltung 4.6. Orientierung 4.7. Farbe als Gestaltungsmittel 4.8. Gestaltung von Knoten 4.9. Gestaltung von Kanten 4.10. Hintergrund 4.11. Anordnung 4.12. Darstellung von großen zweidimensionalen Inhalten 4.13. Zusammenfassung 5. Praktische Umsetzung 5.1. Werkzeuge 5.2. Testfälle 5.3. Umsetzung 5.4. Evaluation 5.5. Zusammenfassung 6. Zusammenfassung und Ausblick 6.1. Fazit 6.2. Diskussion 6.3. Ausblic

Visualizing Information on a Sphere

We describe a method for the visualization of information units on spherical domains which is employed in the banking industry for risk analysis, stock prediction and other tasks. The system is based on a quantification of the similarity of related objects that governs the parameters of a mass-spring system. Unlike existing approaches we initialize all information units onto the inner surface of two concentric spheres and attach them with springs to the outer sphere. Since the spring stiffnesses correspond to the computed similarity measures, the system converges into an energy minimum which reveals multidimensional relations and adjacencies in terms of spatial neighborhoods. Depending on the application scenario our approach supports different topological arrangements of related objects. In order to cope with large data sets we propose a blobby clustering mechanism that enables encapsulation of similar objects by implicit shapes. In addition, we implemented various interaction techniq..